CN111682173B

CN111682173B - Composite material of multi-heteroatom co-doped carbon shell coated silicon and preparation method thereof

Info

Publication number: CN111682173B
Application number: CN202010493828.0A
Authority: CN
Inventors: 韩飞; 刘金水; 项品峰; 汪卫斌
Original assignee: Hunan University
Current assignee: Hunan University
Priority date: 2020-06-03
Filing date: 2020-06-03
Publication date: 2021-12-07
Anticipated expiration: 2040-06-03
Also published as: CN111682173A

Abstract

The invention belongs to the field of negative electrode materials for lithium ion batteries, and in particular relates to a composite material of multi-heteroatom co-doped carbon shell-coated silicon and a preparation method thereof. The composite material uses nano-scale silicon particles as the core and the carbon material co-doped with multiple heteroatoms as the shell, a cavity exists between the silicon core and the carbon shell, and the silicon core and the carbon shell are connected by conductive additives; the The types of heteroatoms in the multi-heteroatom co-doped carbon materials are one or more of four types of N, S, P, and B; the conductive additives are carbon nanotubes, conductive carbon black, graphene, carbon nanofibers one or more of. At the same time, a preparation method and application of the composite material are provided. The prepared material has good cycle performance; the size of the cavity can be regulated by the heat treatment time; and the overall electrical conductivity is good.

Description

Composite material of multi-heteroatom co-doped carbon shell coated silicon and preparation method thereof

Technical Field

The invention belongs to the field of lithium ion battery cathode materials, and particularly relates to a composite material of multi-heteroatom co-doped carbon shell coated silicon and a preparation method thereof.

Background

Compared with a graphite cathode material with the theoretical capacity of only 372mAh/g, the silicon-based cathode material has the advantages of obvious energy density advantage, high theoretical specific capacity of 4200mAh/g, low cost and good environmental compatibility, and is the most potential next-generation lithium ion battery cathode material. However, silicon-based materials face two main obstacles in practical use: (1) the volume expansion of silicon can be caused by 300% in the charging and discharging process, and the huge volume effect causes the collapse of the silicon structure, and finally the capacity attenuation is fast in the circulating process. (2) Silicon is a semiconductor, and the conductivity is much poorer than that of graphite, so that the irreversible degree in the lithium ion deintercalation process is large, and the specific capacity exertion and the charge and discharge efficiency are undoubtedly further reduced.

In order to alleviate the structural damage caused by the volume expansion of the silicon material, researchers mainly focus on designing silicon particles of nanometer scale or constructing silicon particles of cavity type/porous type structures. The nanometer size effect is utilized to reduce the influence caused by the volume expansion of the silicon particles and stabilize the structure of the material; the cavity type or porous type strategy mainly utilizes cavities or porous channels to adapt to the volume change of silicon particles in the lithium intercalation process, thereby ensuring the structural integrity of the material (such as CN 103165874A). The two methods can improve the cycle performance of the silicon cathode to a great extent, but in the practical process of the silicon cathode material, a carbon coating means is an indispensable path. For silicon materials, the carbon coating can well isolate the silicon particles from the electrolyte, and stabilize the surface state of the silicon particles. Meanwhile, the high electron conduction characteristic of the carbon material can improve the charge receiving capacity of the silicon material and improve the utilization rate of silicon particles, so that high reversible capacity is obtained.

Currently, there are a lot of research reports on various carbon coating techniques and carbon coating structures for silicon negative electrodes (e.g., CN 105280890A). However, less work has focused on the modulation of the physicochemical properties of the carbon coating. Because silicon particles and carbon components react to generate SiC at a high temperature of over 1100 ℃, the carbonization temperature is often lower than 1100 ℃ in the carbon coating process, and the lower carbonization temperature can seriously reduce the electronic conductivity of the carbon layer, so that the exertion of the function of the carbon layer is limited. Therefore, considering how to improve the conductivity of the carbon layer as much as possible under the condition of a lower carbonization temperature, the silicon-carbon negative electrode material is a difficult problem to be overcome in the market. In addition, it is also a concern to improve the surface chemical properties of the carbon material and to improve the structural stability of the contact interface between the carbon material and the electrolyte.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a composite material with silicon coated by a multi-heteroatom doped common carbon shell and a preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

a composite material with silicon coated by a multi-heteroatom-codoped carbon shell takes nano-scale silicon particles as a core and takes a multi-heteroatom-codoped carbon material as a shell, a cavity exists between the silicon core and the carbon shell, and the silicon core and the carbon shell are connected through a conductive additive.

The heteroatom species in the multi-heteroatom co-doped carbon material is one or more of N, S, P and B; the conductive additive is one or more of carbon nano tube, conductive carbon black, graphene and carbon nano fiber.

The preparation method of the composite material comprises the following steps:

(1) pretreatment of a carbon precursor: stirring and mixing a carbon precursor and heteroatoms in an organic solvent in a one-pot mixing manner to obtain a doped carbon precursor raw material;

(2) silicon powder oxidation: performing high-energy ball milling treatment on industrial silicon powder and water for 1-4h according to the mass ratio of 1: 0.5-3; then heating the powder to 600-plus-one temperature of 900 ℃ and preserving the heat for 1-4h to obtain SiO₂A mixture of/Si;

(3) carbon coating treatment: mixing the doped carbon precursor and the SiO obtained in the step (2)₂the/Si mixture and the conductive additive are subjected to ball milling treatment according to the mass ratio of 1-3:5:1-0.5, and the carbon-coated composite material is obtained after heat treatment.

(4) Etching SiO₂: placing the carbon-coated composite material in hydrofluoric acid solution to remove SiO₂And filtering, washing and drying the components to obtain the composite material of the multi-heteroatom co-doped carbon shell coated conductive additive and the nano silicon.

In the step (1), the heteroatom type is one or more of four types of N, S, P and B.

The carbon precursor in the step (1) is one or more of medium-temperature pitch, high-temperature pitch, phenolic resin, saccharides and polyacrylonitrile.

The nitrogen source in the step (1) is one or more of melamine, urea, polyacrylonitrile, nitrogen-containing ionic liquid and amino acid, the sulfur source is one or more of sulfur, thiourea and dibenzyl disulfide, the phosphorus source is one or more of red phosphorus, ethylphosphonic acid and triphenylphosphine, and the boron source is one or more of sodium tetraphenylborate, boric acid and borane.

The heat treatment process of the step (3) comprises the following steps: heating to 650-1050 ℃ and preserving the temperature for 1-4 h.

The composite material is applied to a lithium ion battery as a negative electrode material.

Compared with the prior art, the invention has the advantages that:

(1) good cycle performance

According to the invention, various heteroatoms are introduced into the carbon coating layer, and the doping of nitrogen atoms can increase the local charge density of the carbon material to form an n-type semiconductor, so that the electronic conductivity of the carbon material is improved, and the increase of alkaline nitrogen-containing functional groups on the surface can improve the surface wettability of the carbon material and increase the transport and diffusion rates of charge ions; the boron in the carbon structure not only can be used as a catalyst for graphitizing the carbon structure, promote the formation of the graphite structure of the carbon material, increase the electrical conductivity of the carbon material, but also can prevent the carbon material from being oxidized at high temperature; phosphorus and sulfur doping causes an increase in the spacing between the graphite sheets of carbon material, thereby facilitating the reaction of charged ions through the carbon layers with the silicon particles within. In addition, the doping atoms have a synergistic effect relationship, and the phosphorus atom doping can promote the formation of-C-S-C-bond and inhibit the unfavorable-C-SO_x-generation of a C-bond. The heteroatoms act together to promote the formation of a compact and stable solid electrolyte interface film (SEI) on the surface of the carbon material and improve the cycle performance of the silicon carbon material.

(2) Size-adjustable cavity structure

According to the invention, a cavity structure is introduced between the carbon shell and the silicon particles, and the size of the cavity can be adjusted. The existence of the cavity is beneficial to buffering the volume expansion of the silicon particles in the lithium embedding process, so that the structural stability of the silicon particles is ensured, and the negative electrode material has good cycle performance (300 cycles, the capacity retention rate is 85%).

(3) Good overall conductivity

According to the invention, the carbon nano tube, the conductive carbon black or the graphene and other conductive agents are added in the preparation process of the silicon-carbon material, so that the defect of small contact area between the silicon core and the carbon shell caused by the cavity is avoided, the electron transmission speed between the carbon shell and the silicon core is increased, and the overall conductivity of the material is effectively improved.

Drawings

FIG. 1 is a schematic structural diagram of a multi-heteroatom co-doped carbon shell coated silicon composite material in the invention

Fig. 2 is a scanning electron microscope image of the composite material of the carbon nanotube and the nano-silicon coated with the N, S, B, P multi-heteroatom co-doped carbon shell in example 1 of the present invention;

fig. 3 is a transmission electron microscope image of the composite material of the carbon nanotube and the nano-silicon coated with the N, S, B, P multi-heteroatom co-doped carbon shell in example 1 of the present invention;

FIG. 4 is an XPS energy spectrum of a composite material of carbon nanotubes and nano-silicon coated with N, S, B, P multi-heteroatom co-doped carbon shells in example 1 of the present invention;

fig. 5 is a cycle performance diagram of the composite anode material of the carbon nanotube and the nano-silicon coated by the N, S, B, P multi-heteroatom co-doped carbon shell in example 1 of the present invention at 0.5C.

Detailed description of the invention

The present invention will be described in further detail below with reference to examples to enable those skilled in the art to better understand the present invention, but the present invention is not limited to the following examples.

Example 1

(1) Pretreatment of a carbon precursor: weighing 2g of medium-temperature asphalt in a mortar, grinding into powder, pouring into a conical flask filled with 50ml of toluene solution, and stirring for 20 min; and then weighing 2g of melamine, 1g of sublimed sulfur, 0.5g of sodium tetraphenylborate and 1g of red phosphorus, sequentially adding the melamine, the sublimed sulfur, the 0.5g of sodium tetraphenylborate and the 1g of red phosphorus into the solution, carrying out ultrasonic treatment for 10min, and then stirring and evaporating to dryness to obtain the medium-temperature asphalt mixed with the nitrogen source, the sulfur source, the boron source and the phosphorus source.

(2) Silicon powder oxidation treatment: the industrial silicon powder and water are filled into a ball milling tank according to the mass ratio of 1:1, argon is introduced for protection, and then high-energy ball milling treatment is carried out for 2 hours at the rotating speed of 1000 r/min. Transferring the treated powder into a tube furnace, heating to 800 ℃ under the protection of argon, and keeping the temperature for 2h to obtain SiO₂And a mixture of Si.

(3) Carbon coating treatment: mixing the doped asphalt and SiO₂the/Si mixture and the carbon nano tube are filled into a ball milling tank according to the mass ratio of 3:5:1, argon is introduced for protection, and high-energy ball milling treatment is carried out for 2 hours at the rotating speed of 1000r/min to obtain the carbon nano tube and SiO coated by the asphalt₂A composite material of/Si. Transferring the material into a tube furnace, heating to 850 ℃ under the protection of argon, and keeping the temperature for 2h to obtain the carbon nano tube and SiO coated with multi-heteroatom doped carbon₂A composite material of/Si.

(4) Hydrofluoric acid etching treatment: pouring the materials into hydrofluoric acid solution with the mass fraction of 5 wt%, wherein the hydrofluoric acid and the SiO are₂The mass ratio of (A) to (B) is 3:2, and stirring treatment is carried out for 20 min. And after vacuum filtration and water washing, drying at 80 ℃ for 2h to obtain the N, S, B and P multi-heteroatom co-doped carbon shell coated carbon nanotube and nano silicon composite material, wherein the composite material is used as a lithium ion battery cathode material.

SEM result shows that there is no naked nanometer silicon particle, the silicon particle is totally coated by the carbon layer, connect each other between the carbon shells; TEM representation results show that the nanoscale silicon particles are uniformly coated by the carbon layer, and a certain cavity is formed between the silicon core and the carbon layer; XPS results show that the coated carbon layer contains N, S, B and P heteroatoms, and the purpose of co-doping the carbon layer with multiple heteroatoms is achieved.

Electrochemical results show that the first charge-discharge efficiency is 89%, the charge specific capacity is 1490mAh/g, after 500 cycles, the capacity retention rate is 85%, and the cycle performance is stable.

Example 2

(1) Pretreatment of a carbon precursor: weighing 2g of medium-temperature asphalt in a mortar, grinding into powder, pouring into a conical flask filled with 50ml of toluene solution, and stirring for 20 min; and then weighing 2g of melamine, 1g of thiourea and 0.5g of boric acid, sequentially adding the melamine, the thiourea and the boric acid into the solution, carrying out ultrasonic treatment for 10min, and then stirring and evaporating to dryness to obtain the medium-temperature asphalt mixed with the nitrogen source, the sulfur source and the boron source.

(2) Silicon powder oxidation treatment: the industrial silicon powder and water are filled into a ball milling tank according to the mass ratio of 1:0.5, argon is introduced for protection, and then high-energy ball milling treatment is carried out for 3 hours at the rotating speed of 1000 r/min. Transferring the treated powder into a tube furnace, heating to 800 ℃ under the protection of argon, and keeping the temperature for 2h to obtain SiO₂And a mixture of Si.

(3) Carbon coating treatment: mixing the doped asphalt and SiO₂the/Si mixture and the conductive carbon black are filled into a ball milling tank according to the mass ratio of 2:5:1, argon is introduced for protection, and high-energy ball milling treatment is carried out for 2 hours at the rotating speed of 1000r/min to obtain the conductive carbon black and SiO coated by the asphalt₂A composite material of/Si. Transferring the material into a tube furnace, heating to 850 ℃ under the protection of argon, and keeping the temperature for 2h to obtain N, S and B heteroatom doped carbon coated conductive carbon black and SiO₂A composite material of/Si.

(4) Hydrofluoric acid etching treatment: pouring the materials into hydrofluoric acid solution with the mass fraction of 5 wt%, wherein the hydrofluoric acid and the SiO are₂The mass ratio of (A) to (B) is 3:2, and stirring treatment is carried out for 20 min. And after vacuum filtration and water washing, drying at 80 ℃ for 2h to obtain the composite material of conductive carbon black and nano-silicon coated by the N, S and B three-heteroatom doped carbon shell, wherein the composite material is used as a negative electrode material of a lithium ion battery.

Compared with the embodiment 1, the material has no P atom doping, reduces the using amount of water and asphalt and changes the conductive agent into conductive carbon black, has little change of reversible capacity, but reduces the capacity retention rate.

Example 3

(1) Pretreatment of a carbon precursor: weighing 2g of phenolic resin, grinding the phenolic resin into powder in a mortar, pouring the powder into a conical flask filled with 50ml of ethanol solution, and stirring for 20 min; and then weighing 2g of urea and 1g of ethyl phosphonate, sequentially adding the urea and the ethyl phosphonate into the solution, carrying out ultrasonic treatment for 10min, and then stirring and evaporating to dryness to obtain the medium-temperature asphalt mixed with the nitrogen source and the phosphorus source.

(2) Silicon powder oxidation treatment: the industrial silicon powder and water are filled into a ball milling tank according to the mass ratio of 1:3, argon is introduced for protection, and then high-energy ball milling treatment is carried out for 4 hours at the rotating speed of 1000 r/min. Transferring the treated powder into a tube furnace, heating to 800 ℃ under the protection of argon, and keeping the temperature for 2h to obtain SiO₂And a mixture of Si.

(3) Carbon coating treatment: mixing doped phenolic resin and SiO₂the/Si mixture and the graphene are filled into a ball milling tank according to the mass ratio of 2:5:1, argon is introduced for protection, and high-energy ball milling treatment is carried out for 2 hours at the rotating speed of 1000r/min to obtain the graphene and SiO coated by the phenolic resin₂A composite material of/Si. Transferring the material into a tube furnace, heating to 650 ℃ under the protection of argon, and preserving heat for 2h to obtain N and P double-heteroatom doped carbon-coated graphene and SiO₂A composite material of/Si.

(4) Hydrofluoric acid etching treatment: pouring the materials into hydrofluoric acid solution with the mass fraction of 5 wt%, wherein the hydrofluoric acid and the SiO are₂The mass ratio of (A) to (B) is 3:2, and stirring treatment is carried out for 20 min. And after vacuum filtration and water washing, drying at 80 ℃ for 2h to obtain the N and P heteroatom doped carbon shell coated graphene and nano silicon composite material, wherein the composite material is used as a lithium ion battery cathode material.

Example 4

(1) Pretreatment of a carbon precursor: weighing 2g of high-temperature asphalt in a mortar, grinding into powder, pouring into a conical flask filled with 50ml of toluene solution, and stirring for 20 min; and then weighing 1g of dibenzyl disulfide and 1g of triphenylphosphine, adding the dibenzyl disulfide and the triphenylphosphine into the solution, carrying out ultrasonic treatment for 10min, and then stirring and evaporating to dryness to obtain the high-temperature asphalt mixed with the sulfur source and the phosphorus source.

(2) Silicon powder oxidation treatment: the industrial silicon powder and water are filled into a ball milling tank according to the mass ratio of 1:1, argon is introduced for protection, and then high-energy ball milling treatment is carried out for 5 hours at the rotating speed of 1000 r/min. Transferring the treated powder into a tube furnace, heating to 800 ℃ under the protection of argon, and keeping the temperature for 2h to obtain SiO₂And a mixture of Si.

(3) Carbon coating treatment: mixing the doped asphalt、SiO₂the/Si mixture and the carbon nanofibers are filled into a ball milling tank according to the mass ratio of 3:5:0.5, argon is introduced for protection, and high-energy ball milling treatment is carried out for 2 hours at the rotating speed of 1000r/min to obtain the graphene and SiO coated by the asphalt₂A composite material of/Si. Transferring the material into a tube furnace, heating to 750 ℃ under the protection of argon, and preserving heat for 2h to obtain carbon nanofiber and SiO coated with S and P double heteroatom doped carbon₂A composite material of/Si.

(4) Hydrofluoric acid etching treatment: pouring the materials into hydrofluoric acid solution with the mass fraction of 5 wt%, wherein the hydrofluoric acid and the SiO are₂The mass ratio of (A) to (B) is 3:2, and stirring treatment is carried out for 20 min. And after vacuum filtration and water washing, drying at 80 ℃ for 2h to obtain the composite material of the carbon nanofiber and the nano silicon coated by the S and P double-heteroatom doped carbon shell, wherein the composite material is used as a negative electrode material of a lithium ion battery.

Comparative example 1

(1) Silicon powder oxidation treatment: the industrial silicon powder and water are filled into a ball milling tank according to the mass ratio of 1:1, argon is introduced for protection, and then high-energy ball milling treatment is carried out for 2 hours at the rotating speed of 1000 r/min. Transferring the treated powder into a tube furnace, heating to 800 ℃ under the protection of argon, and keeping the temperature for 2h to obtain SiO₂And a mixture of Si.

(2) Carbon coating treatment: mixing medium temperature asphalt and SiO₂the/Si mixture and the carbon nano tube are filled into a ball milling tank according to the mass ratio of 3:5:1, argon is introduced for protection, and high-energy ball milling treatment is carried out for 2 hours at the rotating speed of 1000r/min to obtain the carbon nano tube and SiO coated by the asphalt₂A composite material of/Si. Transferring the material into a tube furnace, heating to 850 ℃ under the protection of argon, and keeping the temperature for 2h to obtain carbon-coated carbon nano tube and SiO₂A composite material of/Si.

(3) Hydrofluoric acid etching treatment: pouring the materials into hydrofluoric acid solution with the mass fraction of 5 wt%, wherein the hydrofluoric acid and the SiO are₂The mass ratio of (A) to (B) is 3:2, and stirring treatment is carried out for 20 min. And after vacuum filtration and water washing, drying at 80 ℃ for 2h to obtain the carbon-coated carbon nanotube and nano silicon composite material, wherein the composite material is used as a lithium ion battery cathode material.

The carbon layer in the silicon-carbon composite material prepared by the method is free of heteroatom doping, and the electrochemical test result shows that the initial capacity of the cathode material is low and is 1321mAh g^-1The cycling stability is poor, and the capacity retention rate after 200 cycles is 81%.

Comparative example 2

(2) Carbon coating treatment: loading the doped asphalt, the industrial silicon powder and the carbon nano tube into a ball milling tank according to the mass ratio of 3:5:1, introducing argon gas for protection, and carrying out high-energy ball milling treatment for 2 hours at the rotating speed of 1000r/min to obtain the asphalt-coated carbon nano tube and SiO₂A composite material of/Si. The material is transferred into a tube furnace, heated to 850 ℃ under the protection of argon gas and insulated for 2h to obtain the composite material of N, S, B and P multi-heteroatom co-doped carbon-coated carbon nano tube and silicon, and the composite material is used as a lithium ion battery cathode material.

Electrochemical results show that the material has a first efficiency of 85%, the specific capacity decays faster from 1857mAh/g to 849mAh/g in the first 100 cycles, and the capacity is much lower than that of example 1.

Comparative example 3

(2) Silicon powder oxidation treatment: industrial silicon powder and water are filled into a ball milling tank according to the mass ratio of 1:1Introducing argon gas for protection, and then carrying out high-energy ball milling treatment for 2 hours at the rotating speed of 1000 r/min. Transferring the treated powder into a tube furnace, heating to 800 ℃ under the protection of argon, and keeping the temperature for 2h to obtain SiO₂And a mixture of Si.

(3) Carbon coating treatment: mixing the doped asphalt and SiO₂the/Si mixture is filled into a ball milling tank according to the mass ratio of 3:5:1, argon is introduced for protection, and high-energy ball milling treatment is carried out for 2 hours at the rotating speed of 1000r/min to obtain the carbon nano tube and SiO coated by the asphalt₂A composite material of/Si. Transferring the material into a tube furnace, heating to 850 ℃ under the protection of argon, and keeping the temperature for 2h to obtain the multi-heteroatom doped carbon-coated SiO₂A composite material of/Si.

(4) Hydrofluoric acid etching treatment: pouring the materials into hydrofluoric acid solution with the mass fraction of 5 wt%, wherein the hydrofluoric acid and the SiO are₂The mass ratio of (A) to (B) is 3:2, and stirring treatment is carried out for 20 min. And after vacuum filtration and water washing, drying at 80 ℃ for 2h to obtain the N, S, B and P multi-heteroatom co-doped carbon-coated nano-silicon composite material, wherein the composite material is used as a lithium ion battery cathode material.

Electrochemical results show that the reversible capacity of the material is low, 1328 mAh/g, after 500 cycles, the capacity retention rate is 76%, and the cycle performance is poorer than that of the sample in the embodiment 1.

Examples of the effects of the invention

The battery negative electrode materials prepared in the examples and the comparative examples are applied to lithium ion batteries, and the performances of the lithium ion batteries are examined.

TABLE 1 analysis of the performance of the negative electrode materials for lithium ion batteries prepared in the examples and comparative examples

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Claims

1. a composite material of multi-heteroatom co-doped carbon shell-coated silicon, is characterized in that, with nano-scale silicon particle as core, with multi-heteroatom co-doped carbon material as shell, between silicon core and carbon shell. There is a cavity between the silicon core and the carbon shell, and the conductive additive is used to connect the silicon core;

The types of heteroatoms in the multi-heteroatom co-doped carbon material are one or more of four types of N, S, P, and B; the conductive additives are carbon nanotubes, conductive carbon black, graphene, carbon one or more of nanofibers;

The preparation method of the composite material specifically comprises the following steps:

(1) Pretreatment of carbon precursor: The carbon precursor and the heteroatom are stirred and mixed together in an organic solvent by a "one-pot mixing" method to obtain a doped carbon precursor raw material;

(2) Oxidation of silicon powder: industrial silicon powder and water are subjected to high-energy ball milling for 1-4 hours according to the mass ratio of 1:0.5-3; then the powder is heated to 600-900 °C for 1-4 hours to obtain SiO ₂ /Si mixture;

(3) Carbon coating treatment: ball milling the doped carbon precursor, the SiO ₂ /Si mixture obtained in step (2), and the conductive additive in a mass ratio of 1-3:5:1-0.5, and heat treatment to obtain Carbon-coated composites;

(4) Etching SiO ₂ : The carbon-coated composite material is placed in a hydrofluoric acid solution to remove the SiO ₂ component, and the conductive additives and nano-materials coated with multi-heteroatom co-doped carbon shell are obtained after filtering, washing and drying. Silicon composites.

2 . The multi-heteroatom co-doped carbon shell-coated silicon composite material according to claim 1 , wherein in the step (1), the types of heteroatoms are four types: N, S, P, and B. 3 . one or more of.

3 . The multi-heteroatom co-doped carbon shell-coated silicon composite material according to claim 1 , wherein the carbon precursor in the step (1) is medium temperature pitch, high temperature pitch, phenolic resin, sugar One or more of polyacrylonitrile and polyacrylonitrile.

The multi-heteroatom co-doped carbon shell-coated silicon composite material according to claim 1, wherein the nitrogen source in the step (1) is melamine, urea, polyacrylonitrile, nitrogen-containing ions One or more of liquid and amino acid, sulfur source is one or more of sulfur, thiourea, dibenzyl disulfide, phosphorus source is one or more of red phosphorus, ethylphosphonic acid, triphenylphosphine or more, the boron source is one or more of sodium tetraphenylborate, boric acid and borane.

5 . The multi-heteroatom co-doped carbon shell-coated silicon composite material according to claim 1 , wherein the heat treatment process in step (3) is: heating to 650-1050° C. for 1-4 hours. 6 . .

6. Application of the composite material of claim 1 as a negative electrode material in a lithium ion battery.